Previously, 12V DC bus voltage has been widely used for motherboards of servers in applications such as data centers. More recently, 48V power distribution has been used, which can provide better efficiency and performance for the high power demands of computing systems in data centres. In current 48V rack-level UPS systems, 48V is directly provided to the motherboards in servers and is converted down in one stage, using one power converter, or one power conversion stage, to a lower voltage level required by CPUs and GPUs, such as from 1V to 3.3V.
Multi-phase Buck point-of-load (POL) converters, as shown in FIG. 1, are the dominant architecture of step down converters in applications for converting 48V to a much lower voltage level (e.g., 1V to 3.3V). As the required inductance value of the Buck converter is directly proportional to the voltage difference between the input and output of the converter, the inductance value increases with increasing voltage difference (such as from 48V to 1V). Accordingly, the volume of the inductors in Buck converter will increase as well, which lowers power density. Additionally, the 48V input voltage increases voltage stress on the switches which leads to higher switching losses. Therefore, there are drawbacks to current approaches for implementing 48V DC bus architecture in applications such as motherboards of servers.